libaudiohal: Implement simple HIDL client

This client requires both HIDL client and server to be of the same
ABI version (e.g. 32-bit).

EffectHalHidl::process and EffectHalHidl::processReverse are stubs.

Some extra warnings are logged due to unimplemented functions
in the legacy HAL.

Bug: 30222631
Change-Id: Id074131dec6d6c4f1031695abcf3ea066e92a5af
Test: Play Music (play / EQ), YouTube, Loopback RTLT, Ok Google on N5X
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 4d2049e..1ca3e09 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -2087,9 +2087,10 @@
     sp<StreamInHalInterface> inStream;
     status_t status = inHwHal->openInputStream(
             *input, devices, &halconfig, flags, address.string(), source, &inStream);
-    ALOGV("openInput_l() openInputStream returned input %p, SamplingRate %d"
+    ALOGV("openInput_l() openInputStream returned input %p, devices %x, SamplingRate %d"
            ", Format %#x, Channels %x, flags %#x, status %d addr %s",
             inStream.get(),
+            devices,
             halconfig.sample_rate,
             halconfig.format,
             halconfig.channel_mask,